Sandstorm Gold, along with larger rivals such as Franco-Nevada Corp. and Silver Wheaton Corp., acquire a portion of a miner's future cash flow in exchange for upfront cash necessary to build the mines.

Also like gold, silver has dropped off recently. Silver is trading at $28 today, and hasn't broken $30 in ... For a less direct play, Silver Wheaton (NYSE:SLW) and Pan American Silver (NASDAQ:PAAS) are among several popular silver mining stocks. Just ...